During hydrocarbon drilling and recovery operations, and in an effort to identify petroleum sources underground, various properties of earth formations are measured by lowering measurement tools into a drilled borehole. For example, field of gravity measurements are taken in boreholes to estimate properties such as formation density. From a geophysical point of view, a high level of precision and repeatability of borehole measurements determine the success of monitoring earth formations.
One of the applications of borehole gravity measurements in formation evaluation includes estimating bulk density and determining porosity and fluid saturation. Borehole gravity meters are able to sense through casing and far away from a borehole. However, such meters require sophisticated techniques (accurate sensors, exact location of the tool, etc.) As a result, tool position and/or depth error occurs due to, e.g., movement of the tool producing variations in depth over repeated measurements. Additional challenges arise in relation to inversion of borehole gravity data. Traditional inversion methods produce the so-called apparent density, which may differ significantly from the true bulk density, especially when the acquired data is contaminated with noise.